Over this 64-year period, the justices issued one-vote majority opinions on 1,205 out of 7,259 cases. That comes to 16.6 percent.The low, or most united term, was 1954, under Chief Justice Earl Warren, when there was only one five-four split, out of 94 cases. A term starts in October of the year mentioned and finishes the following summer. The high, or most divided term, was 2006, under current Chief Justice John Roberts, when 24 of 71 cases, or 33.8 percent, were decided five-four.Chief Justice Roberts doesn’t just hold the single-term record—he beats other chief justices for the greatest share of five-four splits over his career to date: 22.2 percent, versus 20.3 for William Rehnquist, 16.9 for Warren Burger, 11.7 for Earl Warren and 15 for Fred Vinson.
via Is the Supreme Court More Divided Than in the Past? – NYTimes.com.